Time-series measurements of pressure, conductivity, temperature, and water level collected in Puget Sound and Bellingham Bay, Washington, USA, 2018 to 2021

The elevations of the sensors were determined using a combination of Global Navigation Satellite Systems (GNSS) surveys and tape-down measurements. Upon initial sensor deployment at each location, a survey marker was established and at least three one-minute GNSS occupations were performed to establish the marker elevation. The GNSS positions were post-processed with Trimble Business Center software to apply differential corrections from a nearby GNSS continuously operating reference station operated by the Washington State Reference Network (WSRN; http://www.wsrn3.org/) relative to the North American Datum of 1983 (2011 realization) reference frame. Orthometric elevations relative to the NAVD88 vertical datum were computed using offsets from the National Geodetic Survey Geoid12B geoid model. Once the positions of the survey markers were established, synchronous observations of the vertical distance between the survey marker and water surface elevation using a tape measure and depth measurements from the in-situ sensors were used to determine the elevations of the sensors. An estimate of the accuracy of the offset used to convert depth to water-surface elevation relative to NAVD88 was computed by propagating the combined uncertainties in a) the elevation of the survey marker as determined from repeat GNSS occupations, b) the sum of the tape-down measurements (measurements from the survey marker to the water surface) and the computed height of the water column above the pressure sensor as determined from repeat measurements. The maximum uncertainty in the offset across all sites is estimated to be 0.033 m. Uncertainties for each site are included in the metadata of each netCDF file. This uncertainty does not explicitly include instrument accuracy as described in the Attribute Accuracy Report above.